Related:

c,memory,memory-alignment
So I have a void * data of 32 bit unsigned integers which represents the pixels. Is it okay for me to access one of the pixels with a char * and modify the values directly? Or is it better to store my new pixel in a temporary uint32_t variable...

c,c89,post-increment,ansi-c
Let's say I have the following code: int i = 0; func(i++, i++); The increment is happening right after returning the value? Is it guaranteed that the first argument will be 0, and the second argument will be 1?...

c,function,serial-port,posix
I get confused with one line of code: temp_uart_count = read(VCOM, temp_uart_data, 4096); I found more about read function at http://linux.die.net/man/3/read, but if everything is okay it returns 0, so how we can get num of bytes received from that? temp_uart_count is used to count how much bytes we received...

c++,c,openssl,byte,sha1
I have a value stored as an unsigned char * (in C). This holds the SHA1 hash of a string. My goal is to cover the SHA1 key space. Since I'm using <openssl/evp.h> to generate the hashes, I end up with an unsigned char* holding the SHA1 value. Now I...

c,char,segmentation-fault,user-input,scanf
I need to get in one single shot different inputs from one single line. In particular I need to get a single char and then, depending on which char value I just read, it can be a string and an int or a string, an int and another string and...

c++,c,macros
Suppose I have #define DETUNE1 sqrt(7)-sqrt(5) #define DETUNE2 sqrt(11)-sqrt(7) And I call these multiple times in my program. Are DETUNE1 and DETUNE2 calculated every time it is called? Thanks. Please don't downvote this, I really want to know and a search didn't turn up anything definite. ...

c,prng,shift-register
I am trying to understand how change the galois LFSR code to be able to specify the output bit number as a parameter for the function mentioned below. I mean I need to return not the last bit of LFSR as output bit, but any bit of the LFSR (...

c,exec,ipc
I'm trying to figure out how to pass an int using a char pointer. It fails once the int value is too large for the char. This is what I'm trying to figure out: char *args[5]; int i = 20; /*some other code/assignments*/ args[2] = (char *)&i; execv(path, args); How...

c,function,recursion,comma
This question already has an answer here: What does the comma operator `,` do in C? 8 answers In the below block of code, I am trying to understand how the line return reverse((i++, i)) is working. #include <stdio.h> void reverse(int i); int main() { reverse(1); } void reverse(int...

c,armcc,predefined-macro
Is there Predefined-Macros define about byte order in armcc. I am a novice on the armcc.and sorry for my English. In gcc these are macros: __BYTE_ORDER__ __ORDER_LITTLE_ENDIAN__ __ORDER_BIG_ENDIAN__ __ORDER_PDP_ENDIAN__ ... Now I have to use armcc, Is there same like these with armcc? Thank a lot. by the way,the armcc...

c,strlen
As long as I use the char and not some wchar_t type to declare a string will strlen() correctly report the number of chars in the string or are there some very specific cases I need to be aware of? Here is an example: char *something = "Report all my...

c,string,malloc,free
Below is a C program i have written to print different combination of characters in a string. This is not an efficient way as this algorithm creats a lot of extra strings. However my question is NOT about how to solve this problem more efficiently. The program works(inefficiently though) and...

java,c,jni
So I've tried to use the JNI interface to call Java methods from C. Calling static methods is no problem, but I get stuck when I want to call a method on an object. The code is as follows: #include <stdio.h> #include <string.h> #include <jni.h> int main() { JavaVMOption options[1];...

c,opengl
I'm loading a cubemap to create a skybox, everything is fine and the skybox renders properly with a correct texture application. However, I decided to check my program safety with valgrind, Valgrind gives this error: http://pastebin.com/seqmXjyx The line 53 in sky.c is: glTexImage2D(GL_TEXTURE_CUBE_MAP_POSITIVE_X + i, 0, GL_RGB, texture.width, texture.height, 0,...

c,execl
I already used execl() in code, and it worked well. But this time, I really have no idea why it doesn't work. So here's the code that do not work #include <unistd.h> #include <stdio.h> int main() { int i = 896; printf("please\n"); execl("home/ubuntu/server/LC/admin/admin", (char*)i, NULL); printf("i have no idea why\n");...

c,memory-management,out-of-memory,realloc
I'm trying to implement some math algorithms in C on Windows 7, and I need to repeatedly increase size of my array. Sometimes it fails because realloc can't allocate memory. But if I allocate a lot of memory at once in the beginning it works fine. Is it a problem...

java,class,hex
I understand the structure of a java .class file, but when I want to interpret the raw hex data I get a bit lost. This is a hex dump of a class file, excluding the header and constant pool. I understand the header to be the magic number, minor_version and...

c,scope
The following code is for replacing multiple consecutive spaces into 1 space. Although I manage to do it, I am confused in the use of curly braces. This one is actually running fine: #include <stdio.h> #include <stdlib.h> int main() { int ch, lastch; lastch = 'a'; while((ch = getchar())!= EOF)...

c,string,pointers,char
I need to reverse a given string and display it without using the value At[index] notation , I tried the below program using pointers,but it does not print anything for the reverse string, Please help! int main() { char* name=malloc(256); printf("\nEnter string\n"); scanf("%s",name); printf("\nYou entered%s",name); int i,count; count=0; //find the...

c,arrays,compilation,compiler-errors,include
I'm writing a program for vocabulary training, for myself. And the program itself should be available in different languages, atm in German and English. What I want is to have a Main File which manage all and two separate files for the functions in the right language. I compile all...

c,text,alignment
I have to solve a problem that involves left justification string length and leading zeros. I have the following table : BEGIN CLOSE CONCATENATE DELETE END INITIALIZE PRINT WRITE This is produced by a simple program. My problem is to find out how to convert it like that : It...

c,arrays,pebble-watch,cloudpebble
I'm trying to create a simple dice-rolling application in Pebble using C on CloudPebble. I have an array of different die sizes you can scroll through using Up/Down, and you roll (currently just generate a random number, it'll get fancier later) using the middle button. There's also a label at...

c,embedded,stm32,gnu-arm,coocox
I have a STM32F103VCT6 microcontroller with 48kb of SRAM, and recently i've got a memory collision: I have some static variable (lets call it A) located in heap with size of 0x7000 and I wrote some simple function to get info about stack and heap: void check(int depth) { char...

c,integer,compare,bit-manipulation,string-comparison
I have small vectors. Each of them is made of 10 integers which are between 0 and 15. This means that every element in a vector can be written using 4 bits. Hence I can concatenate my vector elements and store the whole vector in a single long type (in...

c,printf,format-string
Using sprintf and the general syntax "%A.B" I can do this: double a = 0.0000005l; char myNumber[50]; sprintf(myNumber,"%.2lf",a); Can I set A and B dynamically in the format string?...

java,hex,hexdump,javax.comm
I am trying to convert a larger value of hex string into bytes. The information which is get about converting signed bytes is the max is 0x7F equals to 127 only. But now mine I want to convert hexa value C6 into bytes which i should receive 198. Are there...

c,while-loop,char,scanf,getchar
getchar() is not working in the below program, can anyone help me to solve this out. I tried scanf() function in place of getchar() then also it is not working. I am not able to figure out the root cause of the issue, can anyone please help me. #include<stdio.h> int...

c,pointers,dynamic-memory-allocation,behavior,realloc
Note, this question is not asking if realloc() invalidates pointers within the original block, but if it invalidates all the other pointers. I'm new to C, and am a bit confused about the nature of realloc(), specifically if it moves any other memory. For example: void* ptr1 = malloc(2); void*...

c,visual-studio-2012,linker,static-libraries
Using VS2012 C/C++: I created and linked a static lib called "libtools" to my project. Calls to functions in the libtools lib worked as expected. I created and linked a second static lib called "shunt" to my project. But when I incorporate a call to a function in shunt, I...

c++,c,nm
The man page of nm here: MAN NM says that The symbol type. At least the following types are used; others are, as well, depending on the object file format. If lowercase, the symbol is usually local; if uppercase, the symbol is global (external) And underneath it has "b" and...

c,arrays,loops,malloc,fread
I'm trying to allocate an array 64 bytes in size and then loop over the array indexes to put a read a byte each from the inputfile. but when I don't malloc() the array indexes, the loop stays in index0 (so each time it loops it replaces the content in...

c,increment,undefined-behavior
I'm using codeblocks and it is giving a different output to other compilers and I can't find a solution to it.What's the undefined behaviour in this program and is there any solution to avoid it? This is the code to print the nth number in a number system with only...

c,go,xlib,cgo
I am creating a simple window manager (code based of the c code in tinywm) in Golang. To use Xlib, I am using cgo, so my header is: // #cgo LDFLAGS: -lX11 // #include <X11/Xlib.h> And I have a variable declaration, like: event := C.XEvent{} And then, I use this...

c,format,sscanf,c-strings
A well known function of the scanf() functions is that you can pass a format to scan input according to this format. For my case, I cannot seem to find a solution searching this and this documentation. I have a string (sInput) as the following: #something VAR1 this is a...